The need for color filtered light is common among hunters, stargazers, and military and security personnel engaged in covert operations. Color filtered light is preferable to white light in that it helps preserve the night vision of the user and nearby individuals. Additionally, filtered light may be more difficult to detect by observers, particularly hostile observers equipped with modem image-intensifiers.
One challenge to providing a system for color filtering a light source is to make the filter mechanism simple to operate. If there are multiple or complex control inputs, a user may accidentally turn on a white light source at a high setting and thus negatively impact the user's night vision with a flash of bright light, or give away the user's location to a hostile observer.
Another challenge to providing a system for color filtering a light source is to enable the user to select the operating mode of the light by tactile sensation only, under conditions of total darkness. In some circumstances, the user may be unwilling to turn the light on until the light is properly set, thus ensuring that detection or loss of night vision does not occur.
One way of providing color filters for a light is to provide translucent lenses in various colors that the user may insert in place of a transparent bulb cover, as disclosed in U.S. Pat. No. 4,697,890 to Crookston. However, a disadvantage of this approach is that changing the filter color of the light requires disassembly and reassembly. This may be difficult to accomplish in the dark, and may be a slow, time-consuming process. Also, disassembly increases the chances of dropping and possibly losing critical parts during the exchange process. Additionally, the use of separate filters presents the disadvantage of having loose parts, which require storage when not in use. Loose parts are also more vulnerable to loss during periods of disuse than filters that are an integral part of the light.
Another approach to providing a variable color light source is to use independent lamps or bulbs, each of a different color or with a separate color filter. However, the use of multiple bulbs increases the number of component parts and raises the cost of manufacturing such a flashlight. Furthermore, the control of multiple light sources may require either more user inputs or more complex electronic switching to take advantage of the separate bulbs. Additional switches or more complex controls may also increase the risk of user error, which could negatively impact the operator's night vision or increase the chance of detection. Additional controls may also raise the cost of manufacturing, and possibly make the device more prone to failure.
Yet another approach to providing a variable color light source is to use a single lamp or bulb, and a wheel fitted with a variety of colored filters, as disclosed in U.S. Pat. No. 3,936,164 to Cohen et al. However, the light disclosed therein is bulky and awkward, in part due to the significant difference in diameter between the flashlight body and the attached color wheel. Further, the rotational axis of the color wheel is parallel to, but offset from, the longitudinal axis of the flashlight body. As a result, the color wheel extends to one side of the flashlight, producing a lopsided and awkward instrument.
Accordingly, there is a need for a color filtered light that is both simple to operate and quickly changeable by the user, even under conditions of total darkness. Further, there is a need for a color filtered light that is reliable, convenient to use, and contains a small number of inexpensive components.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.